In 2017, a small number of Democratic Representatives foolishly objected to certification of electoral votes from several states, but did do improperly and without support from any Democratic Senators. The video shows then-VP Biden presiding over the joint session and firmly, even a bit testily, enforcing the rules against members of his own party, despite how much he had to hate Trump's victory.
This year the Republicans, it appears, will have support from both chambers, so the objections will be in order and will be heard. So VP Pence is unlikely to be put precisely in Biden's position. But he is being urged to open and count uncertified self-appointed electoral slates of Republicans from swing states. God only knows how that would play out, if Trump "won" via his VP accepting, and Republicans upholding, pseudo-slates of electors. Democrats would surely object, from both chambers, and they might get enough appalled Republicans to support them to reject those spurious slates.
But what then? The properly certified slate doesn't automatically replace the rejected one. Those states' electoral votes either 1) disappear, leaving neither candidate with a majority, so that the House votes by state delegation to choose the President, or 2) Congress forms a commission to resolve the dispute over which slates to accept, as in 1876.
But what if the Senate Republicans did vote to reject the challenge to those slates, handing the victory to Trump by accepting slates of self-appointed electors? Then we might have the greatest crisis of legitimacy in US history.
But I expect Pence, despite my disdain for him, to preside properly as Biden did. And as small a majority as the GOP has in the Senate, I expect there are enough Republicans committed to preserving the electoral system to join with Democrats in rejecting such slates.